Platelet functions in long-term antiplatelet therapy and its discontinuation.

The effect of daily oral administration of 250mg aspirin and 200mg ticlopidine on platelet functions was evaluated in 50 patients with thrombophilia. Platelet aggregation was significantly inhibited (60-80% of control) after administration of aspirin for 5 years and of ticlopidine for 1 year. The second purpose of our study was to observe the changes of platelet aggregation, levels of plasma malondialdehyde (MDA), plasma thromboxane B2 (TXB2) and plasma β-thromboglobuline (β-TG) after medication off. In the cases of aspirin administration, platelet aggregation with all aggregation inducing agents increased significantly after medication off. In ticlopidine administration, platelet aggregation with only 5.0μM ADP increased significantly after medication off. Levels of TXB2 β-TG and MDA showed no significant change after medication off. In conclusion, it is very important therapy for the thromophilic patients.